First of all, I'll get the disclaimer out of the way that my dad wrote this game and it's just become available for download (and registration ). So this is admittedly a quick pimp.

Sudoku is an old-school logic puzzle game for Windows. You won't find any fancy graphics or anything, but the gameplay is seriously addictive.

Though the picture above might make it appear to be a mathematical game, it's not: there's only a single rule and there's no math at all. The red numbers are the "puzzle" that you're given, and you have to provide the grey numbers in order to fill the grid. The rule is that the numbers 1 to 9 must appear once (and only once) in each row of 9, each column of 9, and each smaller 3x3 box. There's never any guesswork involved, though on harder puzzles the next step may not be obvious without developing new solving techniques!

Games usually take anywhere from a few minutes (Very Easy or Easy) to an hour (Very Hard).

There's a 28-day free trial, so if you're curious please give it a go! Download it at www.sudoku.com.